The present invention is directed to a method of employing a sound damper for noise reduction in tools and household appliances and to electrical appliances with sound dampers.
Efforts are made in daily life to avoid an excessive creation of noise due to the negative effects thereof on the human condition, for example as a cause of stress. High noise intensities are thereby caused, among other things, by devices or machines that work with the circulation of a gas, such as air.
U.S. Pat. No. 5,979,598, whose disclosure is incorporated herein by reference thereto and which claims priority from German 196 15 917, discloses an intake sound damper for an internal combustion engine that is fashioned as a broadband airborne noise absorber for the intake noises that are impressed on the combustion air taken in by internal combustion engines. In order to achieve the broadband effect, an axial sequence of resonator chambers with volumes that respectively differ from one another is formed in a resonator surrounding an intake pipe, and these resonator chambers are formed by partitions fashioned transverse to the axis of the intake pipe. Each of these resonator chambers is in communication with the intake air guided in the intake pipe via wall openings that are formed in the wall of the intake pipe. By matching the aperture area of the openings, the wall thickness of the intake pipe in the region of the openings and the volume of the resonator chambers, a continuous broadband damping can be set over a great frequency range, in the range, for example, from 1-10 kHz that is of practical interest here. In motor vehicles having an internal combustion engine with a supercharger and a charge cooling, the known intake sound damper is advantageously arranged immediately behind or at or integrated in the pressure joint of the supercharger at a distance preceding the charge cooling in any case.
The object of the present invention is to also enable a noise reduction given tools and/or household appliances operated with electrical motors as compared to internal combustion engines.
This object is achieved by a method of providing a tool or household appliance that is not powered by internal combustion, but is powered by an electrical motor and has an air passage selected from an air intake, an air- or gas-cooled passage or a gas or air exhaust or outlet; and providing a sound damper for noise reduction in the air passage.
It is thereby preferred that the tool and/or household appliance is an electrical appliance, such as a hair dryer, a hair dryer hood, a fume extraction hood, a vacuum cleaner, an exhaust air or, respectively, condensate or clothes dryer, a leaf vacuum, a leaf blower or a hand dryer.
It is also inventively proposed that the sound damper is preceded by at least one filter element that essentially prevents suspended particles, dust and/or fibers from proceeding into the inside of the sound damper.
In addition, an electrical appliance is inventively offered that has an air or gas passage selected from gas-intaking, gas-cooled and gas-expelling and has a sound damper disposed in the passage.
An inventive electrical appliance is thereby particularly characterized in that the sound damper is composed of an intake pipe carrying the intake air and of a resonator housing surrounding this upon formation of a closed annular space comprising an admission connector and a discharge connector as well as openings in the pipe wall of the intake pipe that are connected to the interior of the resonator. The sound damper comprises an axial sequence of a plurality of chamber walls in the resonator extending transverse relative to the longitudinal axis of the intake pipe and surrounding the intake pipe. The chamber walls form resonator chambers of different volumes in the resonator housing that are hermetically delimited relative to one another, and by such an arrangement of the openings in the pipe wall of the intake pipe that each of the resonator chambers communicates with the interior of the intake pipe and none of the chamber walls are thereby bridged.
An electrical appliance is also inventively characterized by openings in the pipe wall of the intake pipe, all of said openings having the same geometrical shape.
The inventive electrical appliance is also characterized by openings in the pipe wall of the intake pipe that all have a circular-cylindrical shape and that all comprise the same diameter.
Moreover, an inventive electrical appliance is characterized by such an arrangement of the openings in the pipe wall of the intake pipe that each of the resonator chambers communicates with the interior of the intake pipe via the same number of openings.
Preferably, an inventive electrical appliance is characterized by such an arrangement of the openings in the pipe wall of the intake pipe that the openings allocated to each of the resonator chambers comprise the same geometric distribution of the intake pipe wall.
Moreover, an inventive electrical appliance is characterized by an oval or flattened oval cross-section of the intake pipe.
Over and above this, an inventive electrical appliance is characterized by a wall section fashioned without openings continuously from the intake connector to the discharge connector, said wall section being in a valley region of the intake pipe with reference to the use-conforming installed position of the intake pipe in the sound damper and of the sound damper in or, respectively, at the electrical appliance.
An inventive electrical appliance is also characterized by a two-shell fashioning of the intake pipe with an axial parting plane. Alternatively, an inventive electrical appliance is characterized by a two-shell fashioning of the resonator housing with an axial parting plane.
Advantageously, an inventive electrical appliance is characterized by the fashioning of the intake pipe as an insert in the resonator housing.
Moreover, an inventive electrical appliance is characterized by admission connectors and discharge connectors applied at the resonator housing.
Finally, an inventive electrical appliance is characterized by an axial sequence of resonator chambers with chamber volumes either steadily decreasing or steadily increasing in a flow direction.
The invention is, thus, based on the perception that the employment of a sound damper fundamentally known for internal combustion engines in tools and household appliances that are operated with alternative electrical energy sources, preferably electrical motors, leads to a considerable minimization of the noise intensity emitted during their operation.
Other advantages and features of the invention will be readily apparent from the following description, the claims and drawings.